"I'm sorry, the jet lag's taken a real whack at my vocabulary
today", says Jake Gyllenhaal four minutes into our
interview, rubbing his forehead as the word "difficult" temporarily
escapes him mid-sentence. It's 12:34pm and we're sitting in a
bed-less suite at London's Connaught Hotel - rather appropriate
considering the actor has barely slept since he arrived in town to
promote his new cop drama End of Watch. Over the past 24
hours he has been up late sitting on Graham Norton's couch, up
early for Nick Grimshaw's Radio One breakfast show and
after a series of brief encounters with the British press will
board another plane back to New York where he's currently tackling
his first professional American stage role. Cup of loose-leaf tea
in hand, Gyllenhaal slouches into an armchair in relaxed indigo
jeans and a navy crewneck jumper - but frankly we can't take our
eyes of his particularly lustrous beard. This "Hollywood
dishevelled" look couldn't be more different to skin-headed,
clean-shaven Officer Brian Taylor, the LAPD cop he plays in End
of Watch alongside beat partner Mike Zavala (played by Michael
Peña). Set on the gang-ridden streets of South Central Los Angeles
and filmed mostly on video cameras held by the characters
themselves, the fast-paced film follows the men as they learn the
price that comes with being hailed as heroes in the city's most
notorious borough. To mark the UK release, Gyllenhaal discusses
undergoing extreme temperatures, key driving skills and the best
advice he's ever received.

GQ: You had to train every morning, get shot at with
live rounds, ride with LA's South Central police three nights a
week for five months and sit inside a burning building in
preparation for this role. Were there any points where you felt it
was too much of a challenge? Jake Gyllenhaal: There were moments where I thought to
myself, "I am just making a movie, how far do I take it?" The very
first ride along I went on someone was killed. But soon, I was just
involved. "Consumed" is the best way I can put it. Every day we
were in real danger, like when we were in the controlled burn,
sitting there in our suits, lifting our hands up to feel that 1000
degree heat. But that was the point of the movie. The strength of
the bond between these two guys that comes out of those situations,
so you need to know those situations in order to portray it. For
every moment where I would think, "This is a movie", I was also
aware that there are people who do this job every day and we need
to do it a service.

You've talked previously about the gallows humour of the
cops you rode with. What was the worst thing they made a joke
about? Michael [Peña] and I were on patrol with two sheriffs and
they got a call to go down this alleyway. They whispered to us that
they could hear something moving and drew their guns. Instinctively
Michael and I began to fall back - if there's potential for anyone
to pull a gun, the situation isn't a whole lot of fun, especially
when you don't have one yourself. All of a sudden we heard gunshots
go off. We soon realised they had set fireworks off. They had
totally messed with us - faked the call, rigged the alleyway - and
we were freaking out that we were in some firefight! I guess it
meant we weren't so shocked in the future, but it was still a
little embarrassing.

What did the police officers say on screen cops often
get wrong? So many things. I think there's a stigma that goes along
with the uniform that gets dramatised in films and on TV - that's a
fantasy and the reality is so much different. One of the things
David Ayer was very serious about was the way in which the driver
in a cop car switches the gears before he exits. It's a very
specific movement that's very rarely done accurately. We worked so
hard to make those moments really real - how we moved, how we held
our guns, how we sat in the car, how we dealt with the suspects… I
think we succeeded.

What's your favourite cop film? I love Training Day - that's a great movie. As
an actor too, I love watching Denzel Washington perform and that was an
incredible performance. Plus the writing at the time was
groundbreaking. There are so many incredible cop films, but I think
the reason this movie is different is that it's not just two cops,
its two best friends. I don't know too many cop movies that do
that.

This film has a great soundtrack. Were there any
particular artists you listened to in preparation for this
role? My character in particular was very intellectual, in a
way. Most movies I do listen to music to psyche myself up, but
there's not anything specific for this one. I wasn't even listening
to music - I was listening to the sound around me. They say you
roll down the window in a cop car and you hear the cries of the
city. You never roll up your window -you need to use all your
senses all the time.

What's the best advice you've ever been given? In work, never have any regrets and always leave
everything on the field. And in life…at times, my grandfather would
say to me, "This too shall pass". That's excellent
advice.

End of Watch is out now.

Nick Carvell

Nick is Fashion Editor of GQ.co.uk. Follow him on Twitter and Instagram at @nickcarvell.